Correct answer for questions 2 and 3?
mmm I see your point -- We'll need to be creative here.
I don't want to add None as an option -- its a poor distractor. One option is to reconfigure the whole batch of alternatives as true / false questions. Too much work.
I think the best option for questions 2 and 3 is to add "Partially correct" for the open options. (Which I've done - -you can change back if you would prefer another solution.)
I think we have a little leeway here - -these are formative learning experiences so in the absence of a definitive correct alternative, we can argue its in the interests of learning ;-)
Good. partially correct works for me. And to reinforce that these are formative learning activities, I added a "check feedback for other options" suggestion in the intro. Also, I revised the intro statement to give a hint that not all of the questions have a "correct" answer--sometimes it's more complicated than a simple "correct".